Packaging apparatus

ABSTRACT

A MACHINE FOR APPLYING FILM COVERS TO PREFORMED TRAYS IN WHICH FILLED TRAYS ARE CONVEYED BY A CONVEYOR CONTINUOSLY THROUGH A SEALING ZONE, A WEB OF FILM IS FED FROM A ROLL THEREOF TO OVERLIE THE TRAYS AS THEY TRAVEL THROUGH THE SEALING ZONE, AND THE FILM IS SEALED TO THE TRAYS BY A PLATEN WHICH MOVES DOWNWARD TO PRESS THE FILM AGAINST THE RIM OF A TRAY, THEN LINEARLY FORWARD IN UNSION WITH THE CONVEYOR CONTAINING TO PRESS THE FILM AGAINST THE RIM FOR A SEALING INTERVAL, THEN UPWARD AND THEN BACK TO REPEAT THE CYCLE, THE FILM BEING CUT BETWEEN SUCESSIVE TRAYS.

Nov. 16, 1971 F. E.'PRINGLE ETAL 3,619,972

PACKAGING APPARATUS 7 Sheets-Sheet 1 Filed Dec. 5, 1969 NOV. 16, 1971 PRINGLE ETAL 3,619,972

PACKAGING APPARATUS 7 Sheets-Sheet 2 Filed Dec. 5, 1969 NOV. 16, 1971 PRNGLE ETAL 3,619,972

PACKAGING APPARATUS 7 Sheets-Sheet 5 Filed Dec. 5, 1969 FIG. 6

NOV. 16, 1971 pRlNGLE ETAL 3,619,972

PACKAGING APPARATUS Filed Dec. 5, 1969 '7 Sheets-Shoot &

NOV. 16, 1971 E PR|NGLE ETAL 3,619,972

PACKAGING APPARATUS Filed Dec. 5, 1969 '7 Sheets-Sheet 5 Nov. 16, 1971 F. E. PRINGLE ET PACKAG ING APPARATUS 7 Sheets-Sheet 6 Filed Dec. 5, 1969 r vza/ U United States Patent U.S. Cl. 53-51 8 Claims ABSTRACT OF THE DISCLOSURE A machine for applying film covers to preformed trays in which filled trays are conveyed by a conveyor continuously through a sealing zone, a web of film is fed from a roll thereof to overlie the trays as they travel through the sealing zone, and the film is sealed to the trays by a platen which moves downward to press the film against the rim of a tray, then linearly forward in unison with the conveyor continuing to press the film against the rim for a sealing interval, then upward and then back to repeat the cycle, the film being cut between successive trays.

BACKGROUND OF THE INVENTION This invention relates to packaging apparatus and more particularly to apparatus for sealing film covers on containers.

The invention is especially concerned with apparatus for heat-sealing film covers on preformed trays or similar containers which have a peripheral flange or rim for faceto-face sealing thereto of a segment of a web of film to form the cover, of the same general class as the apparatus shown in US. Pat. 3,436,894.

SUMMARY OF THE INVENTION Among the several objects of the invention may be noted the provision of improved apparatus of the class above described which, while adapted for rapid operation, is also adapted reliably to seal the film to the containers; the provision of such apparatus in which the containers are conveyed continuously at uniform speed through a sealing zone where the film is effectively sealed thereto; the provision of such apparatus adapted for automatic unloading of the containers after the covers have been applied thereto; the provision of such apparatus adapted to handle containers of various shapes and sizes; and the provision of such apparatus adapted to apply position-printed film to the containers and to provide for registration of the printing with the containers.

In general, apparatus of this invention comprises a conveyor for continuously conveying filled open-top containers one after another through a sealing zone, with their open tops upward. Means is provided for supplying a film to overlie the containers as they travel through the sealing zone. A platen is provided for sealing the film to the top of each container as it travels through the sealing zone. The platen is mounted for movement in an orbital path in which, on each cycle, it moves downward to press the film against the top of a container moving forward with the conveyor, then forward in unison with the conveyor, pressing the film against the top of this container for a sealing interval to effect forward feed of the film and sealing of the film to the rim, then upward away from the container, and then rearward for repeating the cycle. The platen remains parallel to the plane of the conveyor in the sealing zone throughout its orbital path. Means is provided for driving the platen to move it in its orbital path with allowance for movement of the platen at the speed of the conveyor when the platen ice moves forward with the conveyor during the sealing interval.

Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in front elevation of apparatus built according to this invention, broken away in part to reduce the length of the view;

FIG. 2 is a plan of part of FIG. 1, certain parts being omitted;

FIG. 3 is an end view of the apparatus, as viewed from the left of FIG. 1, with parts broken away and shown in section;

FIG. 4 is an end view of the apparatus, as viewed from the right of FIG. 1, certain parts being omitted;

FIG. 5 is a plan of another part of FIG. 1, on a larger scale than FIG. 1;

FIG. SA (on sheet 5) is an enlarged fragment of FIG. 5 with parts broken away and shown in section;

FIG. 6 is a front elevation of the sealing means of the apparatus on the scale of FIG. 5;

FIG. 7 is a view similar to but on a larger scale than FIG. 5 with parts broken away and shown in section;

FIG. 8 is a fragmentary plan of a conveyor and trays carried thereby on half the scale of FIG. 7;

FIG. 9 is a view similar to the lower part of FIG. 7 showing another type of tray which the apparatus is capable of handling;

FIG. 10 is a vertical section on line 10-10 of FIG. 5;

FIG. 11 is a view illustrating a modification;

FIG. 12 is a fragmentary view similar to FIG. 1 showing another modification;

FIG. 13 is a view similar to FIG. 5 showing the FIG. 12 modification;

FIG. 14 is a View similar to FIG. 6 showing the FIG. 12 modification;

FIG. 15 is an enlarged fragment of FIG. 14 with parts broken away and shown in section;

FIG. 16 is an enlarged fragment of FIG. 14 showing a moved position of parts; and

FIG. 17 is an enlarged fragment of FIG. 14 with parts broken away and shown in section.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 7 and 8, there is indicated at T1 a preformed rigid tray T1 of shallow rectangular form to which a lid or cover of a film, such as a transparent plastic film, is to be applied by apparatus of this invention. The tray has an outwardly extending peripheral flange or rim R all around its open top. Referring to FIG. 9, there is shown a preformed rigid triangular tray T2 having a rim R, which is another type of tray to which a film cover may be applied by apparatus of this invention. The triangular type of tray is widely used for packaging sandwiches in commissary and vending operations. The rim R in each instance is for face-to-face sealing thereto of film to form a lid or cover. The trays may be plastic trays, formed, for example, of high density polyethylene, polypropylene, oriented polystyrene or the like, and the film for the lid or cover may be a heat-sealable polyester film, or a foil with a heat-seal coating for being heat-sealed to the trays and may be one that is peelable from the rim R. The trays may be made of material other than plastic, and the film, instead of being heatsealed to the trays, could be sealed thereto by pressuresensitive adhesive (either on the film or on the trays).

Now referring more particularly to FIG. 1, apparatus 3 made in accordance with this invention for applying covers of film to the trays (T1 or T2) is shown to comprise an endless conveyor 1 adapted continuously to convey filled trays one after another at a uniform rate of speed from a loading zone L through a sealing zone S and thence to an unloading zone U. Trays are applied to the conveyor at the loading zone, being filled either before or after being applied to the conveyor, and conveyed through the sealing zone S where a film cover is sealed to the rim R of each tray, and thence conveyed to zone U where the trays with the covers sealed thereon are discharged. At 3 is indicated means for supplying a web of film to overlie the trays as they travel through the sealing zone. At 5 is indicated a platen for sealing the film to the rim of each tray as it travels through the sealing zone.

The conveyor 1 is an endless chain conveyor, having a supporting structure comprising a vertical frame plate 7 supported by a tripod leg arrangement including two outrigger legs 9 at one end and a third leg 9a having adjustable feet 11. It comprises a pair of chains each designated 13 trained around a pair of idler sprockets indicated at 15 on a horizontal shaft 17 journalled in bearings 19 adjacent one end of the frame plate 7 (referred to as its rearward end) and around a pair of drive sprockets 21 on a horizontal drive shaft 23 journalled in a bearing 25 on plate 7 adjacent its other end (referred to as its forward end). The bearings 19 are mounted on a horizontal plate 27 which extends rearward from between upper and lower bracket plates 29 and 31 cantilevered out from the front of the frame plate 7, and which is adjustable longitudinally of the apparatus for chain tensioning purposes. The conveyor has an upper reach designated lu which travels forward from sprockets 15 to sprockets 21, and a lower return reach 1r which travels rearward from sprockets 21 to sprockets 15. The conveyor is adapted to be continuously driven by a motor-speed reducer unit 33 via a first belt and pulley drive 35 and a speed-reducing second belt and pulley drive 37 from the first drive 35 to the drive shaft 23.

The chains 13 carry an endless series of tray carriers, each designated 39. Each tray carrier, as herein shown, is constituted by a relatively thick rectangular plate memher having an opening 41 therein which is dimensioned to receive a tray with the rim R of the tray engaging the outside (upper) face of the carrier 39 all around the opening 41. This opening is made to the shape of the trays to be handled, being rectangular as herein illustrated. A flat resilient rectangular ring 43 may be provided around the opening 41 for engagement by the rim R. Each carrier is secured on its transverse center line at opposite sides of the carrier to a pair of ears 45 on the chain 13. The pairs of ears are spaced at intervals along the length of the chain somewhat greater than the length of a carrier 39, and hence the ends of adjacent carriers are spaced from another as indicated at 47.

With respect to the upper reach lu of the conveyor, as shown in FIG. 1, the chains 13 travel horizontally from the rearward end of the frame plate 7 to a point A somewhat short of the forward end of the frame plate on the upper edges of a pair of spaced chain rails 49. The sprocket shaft 23 and the sprockets 21 at the forward end of the apparatus are located at a lower elevation than the sprocket shaft 17 and sprockets 15 at its rearward end. Rails 49 have downwardly inclined upper edge portions 49a at their forward ends and the chains are inclined downward on these downwardly inclined upper edge portions 49a of the rails to the sprockets 21. The rails 49 are constituted by elongate narrow plate members supported by bolts 51 cantilevered frontward from frame plate 7, with short tubular spacers 53 on the bolts between plate 7 and the inside rail and relatively long tubular spacers 55 on the bolts between the rails (see FIG. 3).

In the upper reach 1a of the conveyor, the tray carriers 39 travel through the loading zone L at a convenient loading height (e.g., thirty-six inches above the floor). The

frame plate 7 is of corresponding height for about half its length throughout the loading zone. The frame plate has an upward extension 7a throughout the remainder of its length. Extending frontward from this extension above the upper reach of the conveyor is an expansible and contractible arbor 57 for carrying a roll PR of the film F, with a friction brake strap 59 for braking the roll for filmtensioning purposes. The film supplying means 3 further includes four guide rolls indicated at 61, 63, 65 and 67 around which the film travels from the roll PR and by means of which it is guided to overlie the trays (such as T1) lodged in the tray carriers 39 as they travel through the sealing zone S. The rolls 65 and 67 are located one above the other adjacent the rearward (left) edge of the frame plate extension 7a. Roll 67 has a resilient (rubber) cover and may be mounted to act as a presser roll for pressing the film down against the flanges of the trays being moved forward by the conveyor. For this purpose, roll 67 is carried by a rocker arm 69 on a shaft 71 journalled in a bearing on plate extension 7a, with a crank arm 73 extending radially from shaft 71 in back of plate 7a biased to swing downward by a tension spring 77. A handle for raising the roll 67 for threading the film is indicated at 75. As shown, the film is unwound from the bottom of the roll PR, and travels forward under roll 61, over and back around roll 63, rearward back to roll 65, over and down around roll 65 to the rear of roll 67 and down around roll 67 and forward over the open tops of the trays, being pressed down against the flanges R of the trays by roll 67 under the bias of spring 77. A printer 79 may be provided for printing such matter as may be desired on the film as it travels around the roll 63.

The sealing zone S is immediately forward of the guide roll 67. The platen 5 is mounted for movement in an orbital path in this zone wherein it moves downward to press the film F against the flange R of a tray T1 carried by a carrier 39 forward of roll 67, then linearly and horizontally forward in unison with the carrier 39 and the tray carried thereby, then upward and then linearly and horizontally rearward, with the platen 5 remaining parallel to the plane of the upper reach of the conveyor in the sealing zone (i.e., remaining horizontal) throughout its stated orbital path. Means mounting the platen for movement in this path is shown to comprise a first crank disk 81 on the front end of a shaft 83 journalled in. a bearing on plate extension 7a, and a second crank disk 85 on the front end of a shaft 87 journalled in plate extension 7a. These disks 81 and 85 are located side-byside, and have eccentric crank pins 89 and 91, respectively, projecting from their front faces. A bar 93 is carried by these crank pins, extending horizontally between them. On rotation of the crank disks 81 and 85 in counter-clockwise direction as viewed in FIGS. 6 and 7, the bar 93 is moved in a path wherein certain points thereof travel in circles around the axes of the disks (i.e., the axes of shafts 83 and 87), the bar remaining horizontal throughout this path. The platen 5 is constituted by a metal sole plate 95 having a recess 97 in the bottom thereof providing a skirt 99 all around the bottom of the platen corresponding to the flange R on a tray T1. The sole plate 95 is carried by a metal head block 101 having electric heaters such as indicated at H in FIG. 7 in recesses 103 therein for heating the platen. The platen 5 is carried by the bar 93 for up and down movement relative to the bar below the bar, and is biased downward toward an extended position relative to the bar. For this purpose, the block has shoulder screws 105 threaded in tapped holes in the top of block 101 and extending upward from the block. A sleeve 107 surrounds the screw and a spacer 109 is interposed between the head of the screw and the upper end of the sleeve. The sleeves are vertically slidable in vertical holes such as indicated at 111 in the bar 93. The platen 5 is biased downward by compression springs 113 accommodated in recesses 115 in the bar and reacting downward against the top of the platen head block 101 from set screws 117 threaded in the bar 93, the downward movement of the platen relative to bar 93 being limited by engagement of spacers 109 with the top of the bar 93. Wiring for the heaters is indicated at 119. A thermo stat block is indicated at 121 and wiring therefor is indicated at 123.

The shafts 83 and 87 have spur gears 125 and 127 thereon at their rear ends in back of plate extension 21a. A drive gear 129 in mesh with both of these spur gears provides-for driving the disks 81 and 85 in unison and in the same direction (counterclockwise as viewed in FIG. 6). Gear 125 is keyed to its shaft as indicated at 131. Shaft 87 and disk 85 are adapted to be angu'larly adjusted relative to gear 127 and hence relative to shaft 83 and disk 81 for accurately phasing the disk 85 relative to the disk 81 by means such as indicated generally at 133 involving a pair of set screws 135 threaded in ears 137 on a collar 139 keyed as indicated at 141 to shaft 87, the set screws engaging opposite sides of a pin 143 projecting radially from the hub 127a of gear 127.

The drive gear 129 for the two disks 81 and 85 is keyed on a shaft 145 journalled for rotation in back of plate extension 7a in a bearing 147. This shaft 145 is adapted to be driven via a belt and pulley drive 149 from a lay shaft 151 on which is keyed the pulley 153 of the belt and pulley drive 35 from the motor-speed reducer unit 33. This shaft also has keyed thereon the pulley 155 of the belt and pulley drive 37 which drives the conveyor drive shaft 23. It is mounted in a frame 156 on the back of plate 7. Drive 149 includes a pulley 157 on shaft 151 with a resilient yielding coupling means generally designated 158 between the shaft 151 and this pulley. This resilient coupling means (see particularly FIG. 5A) comprises a lug 159 on pulley 157 interposed between a set screw 161 threaded in an ear 163 carried on pulley 155 and a spring plunger 165 in an opposed ear 166 on pulley 155. Pulley 157 is free to rotate relative to shaft 151.

Means is provided for coupling the bar 93 and platen 5 carried thereby to the conveyor 1 when the bar 93 and platen 5 move downward and the platen comes into engagement with the rim R of a tray T1 in a carrier 39 so as positively to provide for forward movement of the platen in unison with the conveyor. This means comprises a pair of tongues 167, each of which may consist of a piece of plastic, adapted to enter the space between two adjacent tray carriers 39 as the bar 93 and platen move downward to start a cycle. The tongues are secured as indicated at 169 to the ends of a cross-bar 171 which extends transversely across the bottom of bar 93 slightly forward of the forward end of the platen 5. The length of the crossbar is somewhat greater than the width of the platen, so that the ends of the cross-bar and the tongues 167 lie laterally outward of the sides of the platen and are adapted to straddle the film F.

The cross-bar 171 is secured to the bottom of bar '93 spaced forward from the forward end of the platen 5. A knife blade 173 is mounted for vertically sliding movement in the space between the forward end of the platen and the cross-bar by means of bolts such as indicated at 175 extending through vertical slots 177 in the blade. The blade is biased upward to a raised retracted position wherein its lower edge, which is its cutting edge and which may be serrated, is above the bottom surface of the platen sole plate 95 by leaf springs such as indicated at 179 secured as indicated at 181 to the bottom of the bar 93. The blade is adapted to be driven downward by means of a pair of arms 185 on a rock shaft 187 journalled in the forward end portion of bar 93, this shaft having a crank arm 189 carrying a cam follower roller 191 engageable with a cam 193 on plate extension 7a. Arms 185 are engageable with upwardly extending projections 194 of the blade which lie on opposite sides of bar 93.

Trays exiting from the sealing zone after having had the film'applied thereto and severed travel to the unloading zone U where they are automatically ejected from the tray carriers 39. The ejecting means comprises a series of arms 195 extending radially outward from sprocket shaft 23 (three such arms being shown) spaced at equal intervals around the shaft 23 and each having a crosshead 197 at its outer end. The arrangement is such that as each tray carrier 39 carrying a tray T1 travels down the incline 49a of the rails 49 and travel forward past the forward end of the rails toward the top of sprockets 21, the crosshead 197 on one of the radial arms 195 engages the bottom of that tray T1 and lifts the leading end portion of the tray up out of the opening 41 in the tray carrier, bringing the tray into a generally horizontal position as shown in FIG. 1. The tray continues to move forward since its trailing end is still in the opening 41 of the tray carrier, being pushed forward by the conveyor. As it is so pushed forward with its forward end raised up above the carrier 39, the sides of the rim R of the tray enter horizontal grooves 199 (see FIG. 4) in a pair of opposed rails 201 constituting a discharge conveyor, and the tray is left hanging by the side of its rim from the rails as the tray carrier proceeds on down and around the sprockets 21.

At 203 is indicated a switch actuated by a cam 205 on shaft 83. This switch 203 is interconnected with an on-off switch (not shown) for the motor of unit 33 in such manner and cam 205 is so developed and phased as to provide for stopping of the apparatus only in a raised position of platen 5 relative to the conveyor 1.

When position-printed film (i.e., film having a printed pattern thereon repeated generally at tray length intervals) is to be applied to the trays, the pattern includes a registration mark. At 207 is indicated an electric eye scanner unit of a conventional type used in a system for transmitting a signal whenever the printed pattern on the film becomes out of register with the trays, as determined by scanning of the scanner unit for a registration mark at a predetermined point in the cycle of the platen 5. The signal is utilized to effect correction of registration; for example it may be utilized to apply an electric brake 209 for the film roll arbor FR, which results in stretching of the film when it is pulled forward by the platen and conveyor to bring the pattern back into register with the trays. For this type of correction of registration, the film will generally be printed with the registration marks repeated at an interval slightly less than the length of a tray. 1 Operation of the above-described apparatus is as folows:

With the motor of unit 33 in operation, the sprocket shaft 23 is driven continuously to drive the endless chains 13 of the conveyor 1, thereby continuously moving the tray carriers 39 forward at a constant speed in the upper reach lu of the conveyor. Trays (e.g., trays T1) are placed in the tray carriers 39 as they travel through the loading zone L. The trays may have been filled before they are placed in the tray carriers, or they may be filled after they have been placed in the tray carriers as they travel through the loading zone L. The loading of the trays into the tray carriers and the filling of the trays may be automated, if desired.

The platen 5, being driven by the motor of unit 33, is orbited in synchronism with the conveyor 1. The film F is trained from web roll FR around guide rolls 61, 63, 65 and 67 as shown in FIG. 1 and extends forward from roll 67 between the platen 5 and the tray carriers 39 in the upper reach of the conveyor 1, overlying the trays T1 carried by the tray carriers. As the platen 5 moves downward at the rearward end of its stroke, the skirt 99 of the sole plate of the platen comes into engagement with the film F all around the rim R of a tray T1 carried by a carrier 39 and starts to move linearly horizontally forward with the carrier 39. When the sole plate engages the film around the rim R, its downward movement is arrested, and bar 93 (which yieldably carries the sole plate) moves downward relative to the sole plate against the bias of springs 113. As the sole plate Comes into engagement with the film, the lugs 167 at the forward" end of the sole plate enter the space 47 between two adjacent tray carriers 39, so that the bar 93 and platen are coupled to the conveyor 1 for forward linear horizontal movement of the platen 5 in unison with the conveyor, and with the skirt of sole plate 95 of the platen in register with the rim of the tray carried by the trailing one of these two tray carriers, i.e., with skirt 99 of the sole plate in register with the rectangular ring 43 around the opening 41 in the trailing one of the two tray carriers.

The platen 5 moves linearly and horizontally forward in unison with the tray carrier 39 of the conveyor 1 which lies under the platen for a sealing interval until the platen 5 moves upward away from the tray carrier to disengage the tongues 167 from the space 47 between the two carriers in which the tongues had been engaged. It will be observed that bar 93 carrying the platen 5 moves in a circular path via pin 89 moving in a circle around the axis of disk 81 and pin 91 moving in a circle around the axis of disk 85. The platen first comes into engagement with the film on rim R of a tray T1 carried by a carrier 39 as bar 93 is moving downward about 30 in advance of the lowermost position (the bottom dead center position) of the bar 93 and starts coming out of engagement with the film about 30 after the bar 93 has passed through its lowermost position. Thus, the sole plate 95 of platen 5 remains in engagement with the film for heat sealing it to rim R for about 60 (V6) of the total cycle of 360 of the bar 93. The bar 93 and platen 5 remain coupled to the conveyor 1 for movement in unison therewith via tongues 167 for this heat sealing interval, which corresponds to 60 of rotation of the bar 93.

It will be observed that the tray carriers 39 move forward at a constant speed. The drive 149 is made such that the normal tangential velocity of each of the crank pins 89 and 85 corresponds generally to the conveyor speed. The forward component of speed of the crank pins 85 and 91, bar 93 and platen 5 (carried by bar 93) would normally vary as a sine function from the position 90 trailing bottom dead center to the position 90 forward of bottom dead center. The provision of the resilient coupling means 158 in drive 149 enables variation in the speed of rotation of disks 81 and 85 and crank pins 89 and 91 to accommodate the forward movement of platen 5 at constant speed in unison with conveyor 1 during the sealing interval.

As the platen 5 moves linearly forward in unison with and pressed down toward one of the tray carriers 39, it seals the film to the rim R of the tray T1 carried by this carrier. In the case of heat-scalable film, the heaters H are energized for heating the platen to heat-seal the film to the tray by heat and pressure. In the case of sealing the film to the tray by pressure-sensitive adhesive, the heaters are not energized, and sealing is by pressure only. The platen 5 also functions to pull film from the roll FR to overlie the next tray carrier 39 for covering the tray carried by the latter. Also, as the platen 5 moves forward, the cam follower roller 191 on arm 189 rides up on cam 193, causing arm 189 to swing up and arms 185 to swing down, thus driving the knife blade 173 downward to cut the film between the stated tray carrier and the next carrier forward. Finally, in the unloading zone, the trays with the film covers sealed thereon have their forward ends lifted up by the arms 195, and are thus unloaded from the tray carriers, side portions of the rim of each tray sliding forward in the grooves 199 in the rails 201.

It will be noted that the conveyor 1, the platen 5 and its linkage and guide rolls 61, 63, 65 and 67 are all in front of the plate 7, 7a, and that the motor-speed reducer unit 33 and the drives 35, 37 and 149 are in back of the plate 7. A removable guard such as indicated at 211 may be provided at the front of the apparatus. The plate 7, 7a and various components of the apparatus may be made corrosion-proof (e.g., made of stainless steel). The guard is mounted for easy removal for cleaning the apparatus, which is facilitated by having the drives in back. The platen assembly may not be completely corrosionproof, but is readily removable for clean-up of the apparatus.

Heretofore, with regard to position-printed film supplied to users of packaging machines for covering containers, the printing companies supplying the film have had problems in providing for repeat distances of the printing which are slightly different from the distances required for use in the packaging machine to provide for registration of the printing in the completed packages. For example, the printing presses which are ordinarily used are adapted for repeat printing in even increments (e.g., 6", 6 /2", 7", etc.), Where for purposes of enabling registration of the printing in the packaging operation, the repeat printing should be slightly off such increments (for example, 7.015). Heretofore, it has been sought to provide for this by shrinking or stretching the film in the course of the printing operation, but this is difficult to control. This difficulty may be eliminated by making it possible for the film to be printed in normal manner with standard repeat distances and tolerances, rather than attempting to stretch or shrink it during the printing operation, by modification of the apparatus of this invention to carry out a stretching operation on the film as it is applied to the trays. This is effected, as shown in FIG. 11, by providing for the upper reach of the conveyor 1 to be inclined upwardly at a slight angle as indicated at 1A toward the sealing zone S, then run horizontally through the sealing zone as indicated at 1B, and then incline downwardly at a slight angle as indicated at 1C. The angle of incline in each instance may be 1, for example, and is considerably exaggerated in FIG. 11. The effect of this is to stretch the film as it is applied to a tray, and the amount of stretch may be controlled by suitable selection of the angle of incline or by using adjustable track sections. As shown in FIG. 11, rails 49 are modified to have inclined upper edge portions 49A and 49C for the inclined conveyor reaches 1A and 1C.

It will be understood that trays of different shapes and sizes may be handled by the use of different tray carriers 39 on the chains 13. It will also be understood that each tray carrier may have a plurality of openings 41 for a plurality of trays; e.g., a number of narrow trays might be run side-by-side and provision made for slitting the film longitudinally between trays. It will be further understood that the trays may be multiple-cavity trays instead of single-cavity trays as herein illustrated.

FIGS. 12-17 show a modification of the above, in which the upper reach lu of the conveyor 1 is horizontal throughout its length from its trailing (left) end to its leading (right) end, the rails 49 being straight without having the inclined upper edge portions 49a of FIG. 1 at their forward ends. Also, for cutting the film the knife is positioned one tray length forward (toward the right) from its position of FIGS. 5-7, and means for tucking the film into the space 47 between two carriers 39 is provided at the knife position of FIGS. 5-7.

More particularly, as to the modification shown in FIGS. 12-17, the cross-bar 171 on the bottom of the bar 93 adjacent its forward end is retained. A film clamp bar 211 is mounted for vertical movement at the bottom of cross-bar 171 by means of pins 213 extending up from the clamp bar having heads 215 slidable in vertical holes 217 in the cross-bar. A coil compression spring 219 acts against each of the heads 215 bias the clamp bar 211 downward to an extended position shown as being determined by engagement of each head 215 with a plug 221 adjustably threaded in the lower ends of hole 217. Other suitable means may be used for adjusting the lowered extended position of the clamp bar. The clamp bar has a rubber pad 223 on its bottom and, in the extended lowered position of the bar, the bottom of the pad is slightly below the plane of the bottom surface of the platen sole plate 95.

The above-mentioned tucking means comprises a tucking blade 225 which is mounted for vertical sliding movement on the inside face of the cross-bar 171 .by means of screws 227 extending through vertical slots 229 in the blade and threaded in tapped holes in the cross-bar 171. As herein illustrated, the tucking blade is adapted to be moved up and down by an air cylinder 231, but it will be understood that other suitable means may be provided for actuating the tucking blade. The air cylinder is mounted on top of bar 93 and has a piston rod 233 extending down from a piston therein (not shown) to a connection at 235 with the tucking blade in a hole 237 in the bar 93.

A stem 241 is cantilevered forward from the forward end of bar 93. At the forward end of this stem is a crossbar 243. This is spaced from cross-bar 171 a distance corresponding to the spacing of the tray carriers 39. A knife blade 245 is mounted for vertical sliding movement on the rear face of cross-bar 243 by means of bolts 247 extending through vertical slots 249 in the knife blade and through bolt holes in the cross-bar 243. The knife blade 245 is spaced forward of the tucking blade 225 a distance corresponding to the spacing of the tray carriers 39. Blade 225 is positioned for entry into the space between two successive carriers 39 and blade 245 is positioned for entry into the space between the leading one of these two carriers and the next carrier forward (toward the right).

The knife blade 245 is backed by a pressure plate 251, bolts 247 extending through vertical slots 253 in this plate registering with slots 249 in the knife blade. Coil compression springs 255 react from cross-bar 243 against nuts on the forward ends of the bolts to bias pressure plate 251 toward the right against blade 245 for frictional engagement of the blade with the rear face of the cross-bar 243. The knife blade is normally located in its lowered cutting position of FIG. 17 relative to the cross-bar 243 and friction between it and the cross-bar is sufficient normally to maintain it in this cutting position as it moves down with bar 93 and cuts the film F between two successive trays, but if it should encounter any abnormal resistance to cutting pressure, the knife blade is free to retract upward relative to the cross-bar 243 as they move downward, so as to avoid damaging the knife blade. If the knife blade has moved upward relative to the cross-bar 243, it is necessary to move it back downward to its extended cutting position relative to the cross-bar for the next cutting operation. For this purpose, the pressure plate 251 is provided with a pair of rollers 257 at the top thereof and a shoulder 259 engaging the upper edge of the knife blade. A pair of cams 261 is provided on a rod 263 cantilevered frontward from plate extension 7a these cams being engageable by rollers 257 when the cross-bar 243 (carrying the knife blade 245 and the pressure plate 251) moves upward with bar 93. The cross-bar 243 carries a film clamp bar 211a identical to and mounted in the same manner as film clamp bar 211.

In the operation of the modification shown in FIGS. 12-17, position-printed film F having the printed pattern including the registration mark repeated at intervals slightly greater than the length of a tray T1 is used. It will. be understood that, as the apparatus proceeds in operation with such position-printed film, the film will fall back relative to the trays T1 and become out of register with the trays. When it has become out of register a predetermined amount, the electric eye scanner 201 transmits a signal for correction of the registration. This signal is utilized to actuate the air cylinder 231 to drive the trucking blade 225 downward to its extended position in which it appears in FIG. 16. Then, as the bar 93 (carrying cross-bar 171, clamp bar 211 and the tucking blade 225) moves downward, and before the platen 5 10 engages the film, the clamp bar 211 engages the film and clamps it down against the flange at the trailing end of the tray immediately forward of (leading) the platen (see FIG. 16). Then, the tucking blade 225 moves down into the space 47 between the tray carrier 39 under the platen and the next tray carrier 39 forward and tucks a length of film into this space, as shown in FIG. 16. Due to the tucking in of the film into the space 47, the film I is advanced forward relative to and over the tray T1 to which it is about to be sealed by the platen 5 to bring the film back into register with the tray. Then the platen 5 seals the film to the tray. As long as the film is in a range of acceptable registration with the trays, as determined by the electric eye scanner 201, the tucking blade remains up in its retracted position of FIG. 15 (wherein its lower edge is above the plane of film F at its lowest point of descent).

With the knife blade 225 in its downwardly extended position relative to cross-bar 243 shown in FIG. 17, on each descent of the cross-bar 243 with the bar 93 (and stem 241) the knife blade moves down in the space 47 between the two tray carriers 39 which is one tray length forward of the tucking blade and cuts the film F between the trays in these two carriers. If the knife blade encounters resistance to its downward movement with crossbar 243, it will slide upward relative to cross-bar 243, clamping plate 251 moving upward with it. Then, on the subsequent ascent of the cross-bar 293, rollers 257 engage the cam blocks 261 to drive the plate 251 and knife blade downward relative to the cross-bar 243 to restore the knife blade to its downwardly extended cutting position relative to the cross-bar 243 as shown in FIG. 17.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions Without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limit ing sense.

We claim:

1. Apparatus for sealing film covers on preformed containers comprising a conveyor for continuously conveying filled open-top containers forward one after another through a sealing zone with their tops upward, means for supplying a web of film to overlie the tops of the containers as they travel through said zone, a platen for sealing the film to the top of each container as it travels through said zone, means mounting the platen for movement in an orbital path wherein it moves downward to press the film against the top of a container, then forward in unison with the conveyor pressing the film against the top of said container for a sealing interval to effect forward feed of the film and sealing of the film to the rim, then upward away from the container and then rearward for repeating the cycle, the platen remaining substantially parallel to the plane of the conveyor in the sealing zone throughout said orbital path, and means for driving the platen to move it in said orbital path with allowance for movement of the platen at the speed of the conveyor when the platen moves forward with the conveyor during the sealing interval, wherein said platen mounting means comprises a pair of rotary members having eccentric pins carrying a bar extending generally parallel to the conveyor in the sealing zone, the platen being carriedby said bar for up and down movement relative to the bar below the bar, and having means biasing the platen downward toward an extended position relative to the bar.

2. Apparatus for sealing film covers on preformed containers comprising a conveyor for continuously conveying filled open-top containers forward one after another through a sealing zone with their tops upward, means for supplying a web of film to overlie the tops of the containers as they travel through said Zone, a platen for sealing the film to the top of each container as it travels through said zone, means mounting the platen for movement in an orbital path wherein it moves downward to press the film against the top of a container, then forward in unison with the conveyor pressing the film against the top of said container for a sealing interval to effect forward feed of the film and sealing of the film to the rim, then upward away from the container and then rearward for repeating the cycle, the platen remaining substantially parallel to the plane of the conveyor in the sealing zone throughout said orbital path, and means for driving the platen to move it in said orbital path with allowance for movement of the platen at the speed of the conveyor when the platen moves forward with the conveyor during the sealing interval, wherein said platen mounting means comprises a pair of rotary members having eccentric pins carrying a bar extending generally parallel to the conve'yor in the sealing zone, the platen being carried by said bar for up and down movement relative to the bar below the bar, wherein the driving means is connected to drive said rotary members and has a resilient coupling therein to allow movement of the platen at the speed of the conveyor.

3. Apparatus as set forth in claim 2 having a common driver for said conveyor and said rotary members with a first drive from the common drive to the conveyor and a second drive from the common driver to said rotary members, said resilient coupling being in said second drive.

4. Apparatus as set forth in claim 3 wherein each rotary member comprises a crank disk having an eccentric crank pin, the bar which carries the platen extending between said pins, each disk being mounted on one end of a shaft, and the shafts for the disks being driven via said second drive.

5. Apparatus as set forth in claim 4 having means for adjusting the phase of one disk relative to the other.

6. Apparatus as set forth in claim 1 having means for heating the platen.

7. Apparatus for sealing film covers on preformed containers comprising a conveyor for continuously conveying filled open-top containers forward one after another through a sealing zone with their tops upward, means for supplying a web of film to overlie the tops of the containers as they travel through said zone, a platen for sealing the film to the top of each container as it travels through said zone, means mounting the platen for move ment in an orbital path wherein it moves downward to press the film against the top of a container, then forward in unison with the conveyor pressing the film against the top of said container for a sealing interval to effect forward feed of the film and sealing of the film to the rim, then upward away from the container and then rearward for repeating the cycle, the platen remaining substantially parallel to the plane of the conveyor in the sealing zone throughout said orbital path, and means for driving the platen to move it in said orbital path with allowance for movement of the platen at the speed of the conveyor when the platen moves forward with the conveyor during the sealing interval, wherein the conveyor is an endless conveyor comprising an endless series of container carriers each adapted to hold a filled container and to carry it through the sealing zone with the top of the container upward, and having means movable with and movable relative to the platen mounting means for shifting the film relative to the carriers for registration of printing on the film with the trays, wherein the carriers have spaces therebetween and the means for shifting the film comprises means for tucking the film into the space between two successive carriers, and having means movable with the platen mounting means for cutting the film between two successive carriers, wherein said cutting means comprises a knife blade carried by the platen mounting means one carrier length forward of the tucking means.

8. Apparatus as set forth in claim 7 wherein the knife blade is movable upward relative to the platen mounting means from an extended lowered cutting position wherein it is adapted to enter the space between two successive carriers and a raised retracted position in the event it encounters undue resistance to cutting the film, and wherein means is provided for returning the blade to its lowered cutting position on upward movement of the platen mounting means.

References Cited UNITED STATES PATENTS 3,017,729 1/1962 Cheeley 53-184 X 3,102,626 9/1963 Hanes 53-184 X 3,238,691 3/1966 Miller et al. 53-51 X 3,283,469 11/1966 McBrady et a1. 53-184 X 3,294,301 12/1966 Richter 53-51 X 3,343,336 9/1967 Bradford 53-329 3,427,778 2/1969 McCluskey 53-51 X 3,436,894 4/1969 Sorensen 53-373 3,474,595 10/1969 Moroney et a1. 53-373 3,475,878 11/1969 West 53-51 X 3,490,196 1/1970 Sorensen 53-51 FOREIGN PATENTS 1,119,754 12/1961 Germany 53-184 THERON E. CONDON, Primary Examiner R. L. SPRUILL, Assistant Examiner US. Cl. X.R. 53-329 

